FRANKLIN, Vt. — The red brick house sits unassumingly on a sleepy back road where the lush farmlands of northern Vermont roll quietly into Canada. This is the Morses Line border crossing, a point of entry into the United States where more than three cars an hour constitute heavy traffic.

The bucolic setting of silos and sugar maples has become the focus of a bitter dispute that pits one of America’s most revered traditions — the family-owned farm — against the post-9/11 reality of terror attacks on US soil.

The Department of Homeland Security sees Morses Line as a weak link in the nation’s borders, attractive to terrorists trying to smuggle in lethal materials. The government is planning an estimated $8 million renovation here as part of a nationwide effort to secure border crossings.

It intends to acquire 4.9 acres of border land on a dairy farm owned for three generations by the Rainville family. Last month, the Rainvilles learned that if they refuse to sell the land for $39,500, the government intends to seize it by eminent domain.